Diazaanthracenes ("daas") are heterocyclic analogues of anthracene in which there are two nitrogen atoms in the anthracene framework. The anthracene framework and the numbering system used by the inventors are illustrated below: ##STR1##
It is remarked, however, that on some occasions the prior art uses the following numbering system: ##STR2##
The present invention concerns daas which have one nitrogen atom in each of the terminal or outer rings. There are only six such possible arrangements of daa, which are presented below, along with the corresponding IUPAC nomenclature and the more descriptive names preferred by the inventors. ##STR3##